/*
 * Copyright 2021 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package androidx.activity.compose

import android.view.ViewGroup
import androidx.activity.ComponentActivity
import androidx.compose.runtime.Composable
import androidx.compose.runtime.CompositionContext
import androidx.compose.ui.platform.ComposeView
import androidx.lifecycle.findViewTreeLifecycleOwner
import androidx.lifecycle.findViewTreeViewModelStoreOwner
import androidx.lifecycle.setViewTreeLifecycleOwner
import androidx.lifecycle.setViewTreeViewModelStoreOwner
import androidx.savedstate.findViewTreeSavedStateRegistryOwner
import androidx.savedstate.setViewTreeSavedStateRegistryOwner

/**
 * Composes the given composable into the given activity. The [content] will become the root view of
 * the given activity.
 *
 * This is roughly equivalent to calling [ComponentActivity.setContentView] with a [ComposeView]
 * i.e.:
 * ```
 * setContentView(
 *   ComposeView(this).apply {
 *     setContent {
 *       MyComposableContent()
 *     }
 *   }
 * )
 * ```
 *
 * @param parent The parent composition reference to coordinate scheduling of composition updates
 * @param content A `@Composable` function declaring the UI contents
 */
public fun ComponentActivity.setContent(
    parent: CompositionContext? = null,
    content: @Composable () -> Unit
) {
    val existingComposeView =
        window.decorView.findViewById<ViewGroup>(android.R.id.content).getChildAt(0) as? ComposeView

    if (existingComposeView != null)
        with(existingComposeView) {
            setParentCompositionContext(parent)
            setContent(content)
        }
    else
        ComposeView(this).apply {
            // Set content and parent **before** setContentView
            // to have ComposeView create the composition on attach
            setParentCompositionContext(parent)
            setContent(content)
            // Set the view tree owners before setting the content view so that the inflation
            // process
            // and attach listeners will see them already present
            setOwners()
            setContentView(this, DefaultActivityContentLayoutParams)
        }
}

private val DefaultActivityContentLayoutParams =
    ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT)

/**
 * These owners are not set before AppCompat 1.3+ due to a bug, so we need to set them manually in
 * case developers are using an older version of AppCompat.
 */
private fun ComponentActivity.setOwners() {
    val decorView = window.decorView
    if (decorView.findViewTreeLifecycleOwner() == null) {
        decorView.setViewTreeLifecycleOwner(this)
    }
    if (decorView.findViewTreeViewModelStoreOwner() == null) {
        decorView.setViewTreeViewModelStoreOwner(this)
    }
    if (decorView.findViewTreeSavedStateRegistryOwner() == null) {
        decorView.setViewTreeSavedStateRegistryOwner(this)
    }
}
